ITU-T and ISO/IEC has developed H.264 (MPEG-4 part 10 advanced video coding), which can reduce a lot of bits, to increase the video coding efficiency. For the reference, H.264 uses spatial prediction coding method unlike a conventional video coding standard such as MPEG-1, MPEG-2, and MPEG-4 part 2 visual. The conventional method uses the intra prediction of coefficients converted in the DCT transform domain to increase the coding efficiency. As a result, the conventional method causes generating the subjective image deterioration of the range of low transmission bit-rate. However, the H.264 employs the spatial intra prediction coding method at the spatial domain instead of the transform domain.
As such, the development of the video coding standard brings about a lot of studies on a block matching motion estimation (BMME). Most methods for the BM calculates the sum of absolute differences (SAD) between the block of a current frame and the candidate block of a reference block and determines the position of the candidate block having the smallest SAD as a motion vector of the current frame block.
Residuals between the candidate block and the current frame undergoes the discrete cosine transform (DCT) and the quantization. Then, the residuals undergoes the variable length coding (VLC) along with the motion vector. Here, since finding the motion vector refers to acquiring the motion vector removed with the temporal redundancy of the current frame and the reference frame, the coding efficiency can be considerably increased. However, this process has the following problems.
During the multi-view video coding process, in case that the illumination is changed between inter-views inputted through different cameras in the same time axis or same-views inputted through the same camera in a successive time axis (e.g. scene is changed, or the illumination becomes darker or twinkles in an image), the prior art calculates an SAD between each block and finds the minimum SAD to perform the coding of pertinent residuals. A lot of bits used for the coding are requested, to thereby lower the compressing rate rapidly.
Typically, if there is a scene change, a corresponding intra-frame coding for the changed frame is more efficient than the motion estimate (ME) and motion compensation (MC). This is because the pattern of a current frame block is not found in any area of the searching domain of the reference frame. Similarly, the illumination change or twinkling also takes the same result for the aforementioned process of the ME and the coding of pertinent residuals. Accordingly, the intra-frame coding is mostly applied. In this case, since there was no scene change, a block having the similar pattern to the current frame block can be found. However, even though the residuals of the block and the current frame block are coded, a lot of bits are requested.